Respiratory Failure and Sleep Apnoea Flashcards Preview

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Flashcards in Respiratory Failure and Sleep Apnoea Deck (62)
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1

What is hypoxia defined as

- defined as partial pressure of oxygen in the blood below 8 kPa

2

What is type 1 respiratory failure

- hypoxia - partial pressure of oxygen below 8kPa

3

what is type 2 respiratory failure

- hypoxia - partial pressure of oxygen below 8 kPa
- hypercapnia -partial pressure of carbon dioxide above 6.5 kPa

- carbon dioxide can dissolve in the blood to produce carbonic acid
- pH falls to less than 7.35 in acidosis

4

What is the main function of the lungs

- Ventilation
- gas exchange
- perfusion of the lungs

5

describe the mechanism of a action of ventilation

- intercostal muscles and diaphragm contract
- pressure inside the chest is less than outside
- air is sucked into the lungs
- inspiration takes place
- intercostal muscles and diaphragm relax
- elastic recoil of the lungs forces them to contract
- pressure inside the chest is greater than outside
- air is pushed out of the lungs
- expiration happens

6

What is the mechanism of hypoxia

- hypoventilation
- diffusion abnormality
- ventilation/perfusion mismatch
- right to left cardiac shunt (missing out the lungs)
- low inspired oxygen

7

What is the normal control of ventilation

- stimulation of breathing centre in the brain
- peripheral chemoreceptors of the carotid and aortic bodies

8

What can cause hypoventilation

- Obstruction to airways = asthma at late stage and COPD
- Thoracic cage problems = throacoplasty for TB, Kyphoscoliosis, morbid obesity
- Weakness of respiratory muscles = motor neurone disease and muscular dystrophy

- hypoxia stimulates increased ventilation, unable to increase ventilation = hypoxia and hypercapnia

9

What can cause a V/Q mismatch

Lung airspaces filled with fluid
- lobar pneumonia
- pulmonary oedema

Lung collapse
- pneumothorax
- lung collapse

Area of lung ventilated but not perfused
- pulmonary embolic

- asthma

- Hypoxia leads to increased ventilation
- more carbon dioxide is exhaled
- hypoxic but not hypercapnic

10

What can cause a diffusion abnormality

- Sarcoidosis
- pulmonary fibrosis
- COPD
- asbestosis

- Hypoxia leads to increased ventilation, more carbon dioxide is exhaled = hypoxic but not hypercapnic

11

What can cause low inspired oxygen

- high altitude
- air flight

12

What are the types of respiratory failure

- Type I Acute
- Type I Chronic
- Type II Acute
- Type II Chronic

13

What are the causes of type 1 respiratory failure

Diffusion abnormality
- pulmonary fibrosis
- emphysema in COPD

V/Q mismatch - reduced V
- pneumonia
- pulmonary oedema
- pneumothorax
- lung collapse

V/Q mismatch - reduced Q
- PE

Low inspired oxygen

14

What are the causes of type II respiratory failure

Obstruction to airways
- COPD
- Asthma

Hyper expanded lungs
- COPD

Thoracic cage problems
- Kyphoscoliosis, thoracoplasty
- obesity

Weakness of respiratory muscles
- e.g. MND, DMD

15

How do you treat acute type 1 respiratory failure

- high flow oxygen
- 60-100% oxygen via mask
- keep oxygen stats above 95%
- treat underlying cause - pneumonia, pulmonary oedema, pulmonary embolism, non severe asthma
- consider CPAP if continuing hypoxia

16

What is CPAP

Continuous positive airway pressure

17

How does CPAP work

= pushes pressure into airways mainly during expiration
- can expand collapse portions of the lungs which are under ventilated

18

What is the benefit of CPAP

• Improves ventilation perfusion matching
• Improves hypoxia
• Keeps airway open in sleep apnoea
But
• Does not overcome hypoventilation

19

If you patient is hypoxic you need to give them...

oxygen but not too much oxygen

20

What is acute type II respiratory failure due to

failure of ventilation

21

How do you treat acute type II respiratory failure

Use controlled oxygen therapy
- 0.5 or 2 l/min via nasal cannulae
- 24-28% masks using venturi valves

- aim to keep oxygen 88-92%
- do blood gases regularly to monitor carbon dioxide levels
- consider non invasive ventilation if pH and carbon dioxide is not improving

22

what does non invasive ventilation improve

- hypoventilation
- oxygenation
- prevents or reduces hypercapnia

23

What does non invasive ventilation do

- delivers high pressure during inspiration to improve ventilation

24

What conditions is non invasive ventilation helpful in

- useful in all conditions causing hypoventilation and type II respiratory failure

acute type II respiratory failure
- COPD exacerbations

Chronic type II respiratory failure
- kyphoscoliosis, thoracoplasty
- neuromuscular diseases such as MND, muscular dystrophy
- obesity hypoventilation syndrome
- COPD

25

describe how acute NIV can benefit COPD

• Intubation rate (27% to 15%)
• In-hospital mortality (20% to 10%)
• Complications (mostly ventilator associated pneumonia)
• Length of hospital stay

26

What are the consequences of chronic type I respiratory failure

- pulmonary hypertension
- cor pulmonale
- peripheral oedema
- secondary polycathaemia - stroke
- symptoms from ischaemic heart/peripheral vascular disease
- poor sleep
- neuropsychiatric
- fatigue

27

What do you give for chronic type I respiratory failure

long term oxygen

28

What does long term oxygen therapy do

• Improves survival in COPD patients with hypoxia (PaO2 < 7.3 kPa)

• Reduces complications of hypoxia:
– cor pulmonale
– polycythaemia

29

how long are they given long term oxygen for

Patients given oxygen concentrator to deliver oxygen for at least 15 hours per day

30

what is type I respiratory failure a failure of

failure of oxygenation